Our goal is to increase our biophysical knowledge of cancer and to investigate the role of heavy ions in cancer therapy. Our program project has a strongly interdisciplinary approach. The role of Project I (Cellular and Molecular Radiobiology) is to provide the scientific rationale based on cell biology and to quantitate a variety of normal and tumor cell responses to accelerated ions. We also will explore injury, repair, and cell progression effects, and the modification of heavy ion injury by the cell's environment. Project II (Normal Tissue Radiobiology) is designed to obtain information on the manner in which organized tissues respond to heavy ion injury. Acute, chronic, and late effects are of importance. We will attempt to identify the cellular renewal system that is ultimately responsible for the expression of late injury, and then examine the time dependence for repair, repopulation, and regeneration. The information obtained is of practical use to the therapist, who must protect normal tissues in the course of therapy, and is also of intrinsic scientific value as well. The responsibility of Project III (Radiological Physics) is to provide methods for quantitative measurements of the complex radiation fields, and to understand the physical interactions that are responsible. Two important areas of research are particle fragmentation and track structure. We will also develop mathematical models to tie the physical and biological information into a logical quantitative structure. The Core consists of a committee of project leaders; working in cooperation with the therapists, new directions are developed in the Core to provide maximum support for the ongoing radiotherapy trials using heavy charged particles.